You can access the partner portal at http://tiny.cc/partnerbytes and simply click the register button and use your Malwarebytes email address to sign up for an account to gain access to the portal.
Here also are instructions if you would like to use the portal app on your iPhone or Android device:
For loading the Malwarebytes partner portal app on an iPhone, simply go to the same URL, http://tiny.cc/partnerbytes to download the app, and then go to Settings -> General -> Profiles or Device Management and trust the fonemine app. For Android, you will be prompted during install, simply click “Unknown Sources” and you will have the option to allow the install.